file attachments

Sorry charlesabetz for the late reply. I haven't been able to reproduce your issue, it works fine in my tests. However, I have noticed sometimes it could happen if the HTML email template contain unexpected weird characters in within the dynamic field
or formula.

Dynamics is funny sometimes with the email template design.

Try to open the Email Template within Dynamics, run the Developer tool in IE or Chrome and check exactly the HTML around the dynamic field.